Confirmation of a Transaction

Figure 1. Example of a Confirmed Transaction

┌─────────┐                                 ┌─────────┐
│ PROGRAM │                                 │ PROGRAM │
│         │←───────────────────────────────→│         │
│    A    │                                 │    B    │
└─────────┘                                 └─────────┘

Call ATBALC2           1 
  TP_NAME(B)
  SYNCLEVEL(CONFIRM)

Call ATBSEND           1 

Call ATBCFM (Confirm)  3   ─────────────────→ (LU STARTS PGM B)
  .                       ALLOC, DATA, CONFIRM
  .                                        4  Call ATBGETC
  .
  .                                        5  Call ATBRCVW
  .                                           DATA_RECEIVED=DATA_COMPLETE
  .                                           STATUS_RECEIVED=CONFIRM
  .
  .
  .
RC=OK         7  ←───────────────────────  6  Call ATBCFMD Confirmed)
                             CONFIRMED

Call ATBSEND  8                           Call ATBRCVW
                                              .
                                              .
                                              .

A transaction program can request that its partner confirm that all the data sent so far has been received and processed successfully. In Figure 1:

Program A allocates a conversation with program B, setting the Sync_level parameter to CONFIRM to allow confirmation processing on the conversation.
Program A sends data to program B.
Program A calls the Confirm service. The confirmation request forces the LU to send buffered data.
Program B calls the Get_Conversation service to accept the conversation.
Program B receives the data, checking for completion, and the status received. The status indicates that a confirmation has been requested.
Program B calls the Confirmed service, granting the confirmation. It could have sent an error notification instead, if something was wrong.
The confirmation results in a return code of OK for program A's confirmation request.
Program A continues sending data.